The influence of left ventricular pacing polarity on ventricular repolarization parameters in cardiac resynchronization therapy and its clinical reflections on ventricular tachyarrhythmias

Abstract

Objectives: This study aims to investigate the effects of the left ventricular (LV) pacing polarities on ventricular repolarization patterns and to examine novel parameters taking depolarization into account. Patients and methods: This prospective study included a total of 54 patients (39 males, 15 females; mean age: 65.2±11.6 years; range, 40 to 89 years) with successful cardiac resynchronization therapy using quadripolar LV leads between January 2014 and February 2017. The patients were divided into two groups as the true bipolar group (n=25) and the unipolar/extended bipolar group (n=29). Ventricular repolarization parameters and novel markers, i.e., TpTe/QRS, Tpec/QRS, TpTe/(QRS ¥ QTc) and Tpec/(QRS ¥ QTc), were measured before implantation within 48 h following the procedure and at six months. Evaluation of ventricular tachyarrhythmias was performed using device records during follow-up. Results: The median follow-up was 17.7 (range, 12.6 to 31.2) months. The mean ejection fraction was 23.3±5.5% in the bipolar group and 23.62±6.24% in the unipolar/extended bipolar group. Bipolar LV pacing was associated with higher Tpec/QTc values (acute, bipolar vs. unipolar, +0.011 vs. -0.0008, p=0.019; long-term, bipolar vs. unipolar, +0.005 vs. - 0.015, p=0.005, respectively). There was no significant difference between the groups in terms of other repolarization parameters. Bipolar pacing was associated with significantly higher novel markers values and more frequent sustained and non-sustained ventricular tachyarrhythmias. Conclusion: The LV pacing polarity significantly affects Tpec/QTc, but not the other ventricular repolarization parameters. Novel arrhythmia predictors, i.e., TpTe/QRS, Tpec/QRS, TpTe/(QRS x QTc), and Tpec/(QRS x QTc), are more influenced in bipolar pacing associated with more frequent ventricular tachyarrhythmias.